In Long Term Evolution (LTE), single carrier frequency division multiple access (SC-FDMA) transmission may be selected for the uplink (UL) direction such as by using discrete fourier transform spread orthogonal frequency division multiplexing (DFTS-OFDM). A LTE wireless transmit/receive unit (WTRU) in the UL may transmit a limited, contiguous set of assigned sub-carriers with Frequency Division Multiple Access (FDMA). For example, if the overall orthogonal frequency division multiplex (OFDM) signal or system bandwidth in the UL includes useful sub-carriers numbered 1 to 100, a first WTRU may be assigned to transmit its own signal on sub-carriers 1-12, a second WTRU may transmit on sub-carriers 13-24, and so on. An evolved NodeB (eNodeB) may receive the composite UL signal across the entire transmission bandwidth from one or more WTRUs at the same time, but each WTRU may transmit on a subset of the available transmission bandwidth.
Transmit power of a WTRU may be determined in the WTRU based on measurements made by the WTRU and control data received from the eNodeB. WTRU transmit power control may be needed for maintaining quality of service (QoS), controlling inter-cell interference, and managing a terminal's battery life. LTE advanced (LTE-A), includes features such as bandwidth extension using carrier aggregation, UL multiple-input multiple-output (MIMO), and simultaneous physical uplink shared channel (PUSCH) and physical uplink control channel (PUCCH) transmissions, that may impact WTRU transmit power control.
It is desirable for uplink power control in LTE to compensate for long-term fading, such as pathloss or shadowing, while reducing inter-cell interference and avoiding occurrences of the WTRU using a maximum power procedure to prevent its power amplifier (PA) from operating beyond its linear region and/or to prevent the WTRU from exceeding maximum transmit power limits that may be imposed by the network, regulatory requirements, or the like. Transmit power for LTE uplink may be determined using open loop and closed loop power control that may be predicated on the WTRU transmitting on one component carrier (CC) with one antenna/power amplifier combination. LTE-advanced (LTE-A) includes bandwidth extension using carrier aggregation, where the WTRU may transmit simultaneously on multiple component carriers (CCs). It is desirable to provide ways for determining transmit power when using multiple CCs such that the PAs of the WTRU operates within limits.